Tamara Beckwith is an unlikely pub landlady. The It girl-turned-gallery owner doesn’t drink beer, can’t pull a pint and admits pubs are not her natural habitat. “I’ve never been a regular [anywhere],” she says, in her husky but poshly clipped voice. “Beer doesn’t really agree with me, and it’s very bad for girls’ bottoms — it is ginormous for the bottom.”

Yet that unbroadened-by-beer-bottom is sitting in The Imperial Arms on King’s Road — the Victorian pub that she and her former agent Ghislain Pascal have just invested in. And minutes earlier, it was perched on the bar as the photographer snapped away and Pascal teased: “It’s not Hooters!”

So why has she poured her money and promotional powers into a pub? “Ghislain took advantage of my nice nature,” Beckwith jokes. “To be frank, I wouldn’t have thought of going into the pub business if it wasn’t for him. But we needed another space [to show photographs]: our gallery, though gorgeous, is very bijou.”

At 42, Beckwith still looks like a Badass Barbie, little changed from the twentysomething who made party-going her profession in the Nineties and whose boyfriends included Sylvester Stallone, Charlie Sheen and Sharon Stone’s brother, Michael — a former cocaine dealer.

Back then, she was famous for being rich (her father is property tycoon Peter Beckwith), good-looking and on every guest list, but she has spent the past four years recasting herself as a businesswoman. Her main focus — apart from her two daughters, 25-year-old Anouska and three-year-old Violet — is The Little Black Gallery, a photography space she and Pascal opened almost four years ago, but she also writes and is a contributing editor for her friend Caroline Stanbury’s luxury shopping business, Gift-Library.

Investing in a pub — when they are closing at a rate of two a week — still seems a brave move, though. But the pair, alongside owners Iain and Amelia Heggie, have a fresh take on the local boozer: theirs will sell street food from the popular collective Eat St, rather than the now common gastropub fare.

So will she ever get to pull a pint? “I am sure on the relaunch night I will be allowed to but I don’t know if they think I’d be very good. There’s nothing worse than watching someone who is hesitant. I don’t know if any of my friends drink pints, either — pints of vodka maybe, not pints of Foster’s.”

Ah, those friends, who are testament to Beckwith’s hard-partying years, which started when she was a teenager. Her adolescent metamorphosis turned her into the archetypal parental nightmare: getting into trouble at Cheltenham Ladies’ College for her hair and then — rather more significantly — getting pregnant at 16 by her American boyfriend William Gerhauser.

Beckwith’s parents helped raise the baby girl, Anouska, and Beckwith was later arrested for drink-driving. Though open about her mistakes, she is clearly well versed in batting away awkward questions.

She stresses particularly how grateful she is to her parents: “If you have a good family and you’re really in the shit, you know if you go home it will be all right in the end. Even when I’ve done stupid things and they probably want to throw me off a bridge, luckily they haven’t.”

Anouska, who is now 25, has criticised her mother, though. In an interview last year, she accused Beckwith of partying hard when she was young and said most of her childhood memories are of her grandparents.

The deflection machine here comes into full swing: “How I remember it and how she remembers it are two totally different stories ... Anouska is a Pisces, so if she is asked a question, she will answer. And she also doesn’t have the experience of doing so many interviews. Luckily, she’s got a very understanding and sweet and kind, compassionate mother.”

Beckwith maintains that she is close to Anouska, who is now studying photography in Paris: “She calls me at least three times a day — we’re probably a bit too close because she doesn’t have a lovely dad like my little one does so if she’s feeling a bit pissed off with life, I’m the punching bag.”

The “lovely Dad” to Violet (“Vivi”) is Giorgio Veroni, an Italian property magnate whom Beckwith married in 2007. They met at a party in 1994 (he had brought Sheherazade Goldsmith as a date, Beckwith had turned up with a “dodgy boyfriend”) and were friends for years before they became a couple. He is often credited with helping turn her from socialite to responsible mother but Beckwith jokes that he preferred her as she was before. “I think I am almost too settled now — I think he wishes he could have me back to how I was before! Giorgio is the light of every party.”

He has, though, brought her closer to religion. Even though Beckwith has no plans to convert, they married in a Catholic service in Italy, Vivi is being brought up Catholic, and the trio attend mass at the Oratory, where their priest Father Ronald is “like family — he texts me”.

Of her daughters, it is Vivi who seems more likely to follow in her mother’s footsteps. “Anouska doesn’t like being in trouble, [whereas] I didn’t care as long as the fun outweighed the trouble. I have a feeling Vivi is much more like that — she has got a much more wild personality ... she is 10 foot tall and bulletproof because everything revolves around her in our house.”

Given their place in the public eye, Beckwith is especially concerned that Vivi will feel pressure over her appearance and weight growing up. “Her nonna [grandmother] was freaking out recently, because Vivi’s really skinny [whereas] when she was born she was like a Buddha... I don’t want to make her think she has got to eat everything, because then at seven or eight, when her real weight will come along, I don’t want to have to put her on a diet.”

Beckwith is thick-skinned about such scrutiny herself, though. “I think I’ve always quite liked having lots of attention whether it’s good or bad. If I got upset every time someone said something horrible, I’d just be in a clinic somewhere shivering.”

That said, she believes the British commit reverse-snobbery when it comes to the privileged. “In England, they automatically assume you have your head in the clouds and that you’re going to be a bitch and that you’re spoilt and spend all your days having manicures and pedicures. I wouldn’t ever want to live that life, even if I could.”

But a group of those who do want their lives to look that way — the Made in Chelsea cast — have been known to hang out at The Imperial Arms. Does she consider today’s reality TV stars the heirs to the It girls?

“If you look back, when I was probably 14 or 15, you had the page 3 girls,” she recalls. “It’s just whoever the boys and girls of the moment are.”

Hugo Taylor, who created the Made in Chelsea show, is her daughter Anouska’s ex, but Beckwith doesn’t think much of the series or the cast, calling Caggie Dunlop “the prettiest” but branding cast member Millie Mackintosh “so insipid”.

“I prefer the Liverpudlian one [Desperate Scousewives] where I don’t understand a word,” Beckwith says. “When you look at them [the Made in Chelsea cast] — other than Hugo — they’re not the kids you see in the King’s Road because... the kids who are really friends with Beatrice and Eugenie can’t talk about them. And all of the houses aren’t their houses — they are all outside Eaton Square. Well, I live round there and I’ve never seen any of living there.” If she does become a regular in her own pub, though, that might be about to change.